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Methomyl Page 1 of 7
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<br /> PMfiP Home Page ®Pesticide 4erire t teredient 16ommon �EXTOXNEC,'Hte Extension iocicology Network ®Halox.fon mMethyl Parathion ®Met6omyl
<br /> E X T O X N E T
<br /> Extension Toxicology Network
<br /> V A Pesticide Information Project of Cooperative Extension Offices of Cornell University,Michigan State University,Oregon State
<br /> University,and University of California at Davis.Major support and funding was provided by the USDA/Extension Service/National
<br /> Agricultural Pesticide Impact Assessment Program.
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<br /> Pesticide Methomyl
<br /> Information
<br /> ` Profile Publication Date:9/93
<br /> TRADE OR OTHER NAMES
<br /> Common names include metomil and mesomile.Trade names include Lannate,Lanox,Methavin,and Nudrin.
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<br /> REGULATORYSTATUS
<br /> r. Methomyl is classified as Restricted Use Pesticide(RUP)by the Environmental Protection Agency because of its high
<br /> acute toxicity to humans(28).Restricted Use Pesticides may be purchased and used only by certified applicators.Reentry
<br /> periods for farm workers of 1 to 7 days are required,depending on the crop(30 .Check the product label for details.
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<br /> INTRODUCTION
<br /> Methomyl was introduced in 1966(26)as a broad spectrum insecticide.It is also used as an acaricide to control ticks and
<br /> spiders.It is used for foliar treatment of vegetable,frit and field crops,cotton,commercial ornamentals,and in and
<br /> around poultry houses and dairies. It is also used as a fly bait(6).Methomyl is effective in two ways:(a)as a'contact
<br /> 6. insecticide,'because it kills target insects upon direct contact,and;(b)as a'systemic insecticide'because of its capability
<br /> to cause overall'systemic'poisoning in target insects,after it is absorbed and transported throughout the pests that feed on
<br /> treated plants.It is capable of being absorbed by plants without being'phytotoxic'or harmful,to the plant. It is one of a
<br /> class of chemicals called'carbamates'(8, 13 15 25).The carbamates work by inhibiting cholinesterase,an essential
<br /> k„ enzyme for proper functioning of the nervous system.
<br /> TOXICOLOGICAL EFFECTS
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<br /> ACUTE TOXICITY
<br /> Me[homy]is potentially a highly poisonous material in humans(6).It is highly toxic if it is ingested or absorbed through
<br /> the eyes,moderately poisonous when inhaled,but of lower toxicity with skin,or'demral,'exposure(lg,30).Methomyl is
<br /> a highly toxic inhibitor of cholinesterase,an essential nervous system enzyme.Symptoms of anti-cholinesterase activity
<br /> r. include weakness,blurred vision,headache,nausea,abdominal cramps,chest discomfort,constriction of pupils,sweating,
<br /> muscle tremors,and decreased pulse.If there is severe poisoning,symptoms of twitching,giddiness,confusion,muscle
<br /> incoordination,slurred speech,low blood pressure,heart irregularities,and loss of reflexes may also be experienced.
<br /> ` Death can result from discontinued breathing,paralysis of muscles of the respiratory system,intense constriction of the
<br /> openings of the lung,or all three(6, 16).The onset of symptoms may be delayed up to 12 hours(M).The route,duration,
<br /> and concentration of methomyl exposure will affect the severity of poisoning and the number and types of symptoms that
<br /> occur.Complete recovery from an acute poisoning by methomyl,with no long term health effects,is possible if exposure
<br /> v ceases and the victim has time to reform their normal level of cholinesterase and to recover from symptoms(7,26).(For
<br /> more information on cholinesterase,please refer to the Toxicology Information Brief on Cholinesterase-Inhibition).
<br /> Carbamates generally are excreted rapidly and do not accumulate in mammalian tissue.If exposure does not continue,
<br /> cholinesterase inhibition reverses rapidly.In non-fatal cases,the illness generally lasts less than 24 hours(32).
<br /> Lhttp://pmep.cce.comell.edu/profiles/extoxnet/haloxyfop-methylparathion/methomyl-ext.htrnl 1/2/2004
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